P RO D U C T I N F O R M AT I O N
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T E M P E R AT U R E L I M I T F O R
E X P L O S I O N - H A Z A R D O U S D U S T S
In areas which are explosion-hazardous due to combu-
stible dusts, the surface temperature must not exceed
two-thirds of the ignition temperature in °C of the
dust/air mixture. The temperatures of surfaces on which
hazardous deposits of combustible dusts can be formed,
must not exceed the glow temperature of the relevant
dust minus 75°K. Greater safety margins are required if
thickness of the dust layer exceeds 5 mm.
The corresponding surface temperatures can be derived
from the lowest values for glow and ignition tempera-
tures of dusts specified in the HVBG/BIA Report 12/97
9
"Combustion and explosion characteristics of dusts":
Synthetic rubber, soot-containing:
Glow temperature 220°C - 75°C = 145°C
max. permissible
surface temperature
Stearic acid:
Ignition temperature 190°C x 2/3 = 126°C
max. permissible
surface temperature.
PLEASE AL SO OBSERVE YOUR
CORRESPONDING NATIONAL REGUL ATIONS.
1
Guideline 94/9/EC OF the European Parliament and the Council of 23 March 1994 on the approximation of the laws of
the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres
2
DIN EN 1127-1: Explosive atmospheres - Explosion prevention and protection - Part 1: Basic concepts and methodology,
1997-10
3
IEC 60079-12: Electrical apparatus for explosive gas atmospheres, Part 12: Classification of mixtures of gases and
vapours with air according to their maximum experimental safe gaps and minimum igniting currents, 1978.
4
IEC 60079-20: Electrical apparatus for explosive gas atmospheres, Part 20: Data for flammable gases and vapours,
relating to the use of electric apparatus, 1996-10.
5
DIN VDE 0165: Installation of electrical systems and equipment in areas with explosion hazard, 1991
6
Nabert, Schön: Sicherheitstechnische Kennzahlen brennbarer Gase und Dämpfe 2nd edition, 1978
7
Redeker, Schön: 6. Nachtrag zu Sicherheitstechnische Kennzahlen brennbarer Gase und Dämpfe, 1990
8
DIN EN 50014 (VDE 0170/0171 part 1): 2000-02
Electrical apparatus for use in explosion hazardous areas: General provisions
9
HVBG/BIA-Report 12/97: Central association of German employer's liability associations/Trade association institute
for industrial safety
